Upstream NAI Pressure-Transducer-Signal Failure on Channel B

TASK 30-21-00-810-809-A
Upstream NAI Pressure-Transducer-Signal Failure on Channel B

1. Possible Causes

W03 HARNESS [4087KS]
PRESS XDCR-ENGINE AIR INTAKE ANTI ICE, 1 [4002DN]
[4000KS]

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	PLIERS - JAWED, SOFT

B. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 71-00-00-810-835-A	Component and Harness Intermittent Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults
AMM 30-21-22-000-801	Removal of the Nacelle Anti-Ice Core-Pressure-Transducer
AMM 30-21-22-400-801	Installation of the Nacelle Anti-Ice Core-Pressure-Transducer
AWM 715134
AMM 73-21-00-710-806	Test No.7 - EEC Operation Test (Self Test)
AMM 73-21-01-000-801	Removal of the Electronic Engine Control (EEC)
AMM 73-21-01-400-801	Installation of the Electronic Engine Control (EEC)
AMM 73-21-63-000-802	Removal of the Electronic Engine Control (EEC) Wiring Harness (W03)
AMM 73-21-63-400-802	Installation of the Electronic Engine Control (EEC) Wiring Harness (W03)
AMM 78-36-00-010-802	Opening of the Thrust Reverser Cowl-Doors
AMM 78-36-00-410-802	Closing of the Thrust Reverser Cowl-Doors

3. Fault Confirmation
Subtask 30-21-00-710-064-A ** ON A/C NOT FOR ALL

A. Test
Do the EEC system test AMM 73-21-00-710-806.
(1) If the maintenance message does not come into view again, do the component and harness intermittent for guidance troubleshooting intermittent faults (Ref. TSM TASK 71-00-00-810-835).
(a) If you find no fault, send the engine back to service and monitor the engine to make sure that the maintenance message does not come into view again.
(2) If the maintenance message comes into view again (hard fault) for Channel B, go to the Para. Fault Isolation.

4. Fault Isolation

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AFTER SHUTDOWN. THE ENGINE CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.

CAUTION: MAKE SURE YOU REMOVE ELECTRICAL POWER FROM THE EEC BEFORE YOU REMOVE THE ELECTRICAL CONNECTORS. IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE EEC CAN OCCUR.

Subtask 30-21-00-810-058-A ** ON A/C NOT FOR ALL

A. If there is confirmation of the fault:
(1) Open the right thrust reverser cowl-door AMM 78-36-00-010-802.
(2) Make sure that electrical connector P20 of the W03 harness is correctly engaged in the socket of the NAI core pressure-transducer.
(a) If it is not correctly engaged, engage it.

Do the test given in Para. 3.

(3) If the fault continues, disconnect the electrical connector P20 and do a visual inspection of the electrical connector P20 and of the receptacle J20 of the NAI core pressure-transducer for bent pins, contamination or corrosion or visual signs of damage.
(a) If you find damage on the electrical connector P20:

Replace the W03 HARNESS [4087KS] AMM 73-21-63-000-802 and AMM 73-21-63-400-802.
Do the test given in Para. 3.

(b) If you find damage on the receptacle J20:

Replace the PRESS XDCR-ENGINE AIR INTAKE ANTI ICE, 1 [4002DN] AMM 30-21-22-000-801 and AMM 30-21-22-400-801.
Do the test given in Para. 3.

(c) If you find no damage on the receptacle J20 and the electrical connector P20:
1 Do a resistance check AWM 715134 between:
. Pin J20/6 and pin J20/8 of the NAI core pressure-transducer
. Pin J20/7 and pin J20/9 of the NAI core pressure-transducer.
a If the resistance is more than 12.5 kohm:

Replace PRESS XDCR-ENGINE AIR INTAKE ANTI ICE, 1 [4002DN] AMM 30-21-22-000-801 AMM 30-21-22-400-801.
Do the test given in Para. 3.

b If the resistance is less than 12.5 kohm, use PLIERS - JAWED, SOFT to disconnect electrical connector P14 from the EEC.

Do a visual inspection on the electrical connector P14 of the WO3 harness for bent pins, contamination, corrosion or visual signs of damage.

c If you find damage on electrical connector P14:

Replace the W03 HARNESS [4087KS] AMM 73-21-63-000-802 and AMM 73-21-63-400-802.
Do the test given in Para. 3.

d If there is no damage or if fault continues, do a continuity check AWM 715134 of the W03 harness between:
. Pin 14/MM of the EEC and pin P20/9 of the NAI core pressure-transducer
. Pin P14/r of the EEC and pin P20/8 of the NAI core pressure-transducer
. Pin P14/EE of the EEC and pin P20/7 of the NAI core pressure-transducer
. Pin 14/V of the EEC and pin P20/6 of the NAI core pressure-transducer

If there is no continuity:
Replace the W03 HARNESS [4087KS] AMM 73-21-63-000-802 and AMM 73-21-63-400-802.
If there is continuity:
Replace the [4000KS] AMM 73-21-01-000-801 AMM 73-21-01-400-801.
Do the test given in Para. 3.

5. Close-up
Subtask 30-21-00-942-051-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.
(1) Make sure that the work area is clean and clear of tools and other items.
(a) Close the right thrust-reverser cowl-door AMM 78-36-00-410-802.

[Rev.8 from Aug 2018] 2026.04.04 04:29:31 UTC